I'm pretty confused here as to why [saw] is preferred in the sentences below.
When I was in Tokyo, I saw the movie three times.
When I was in Tokyo, I had seen the movie three times.
I'm not sure but my understanding is, saw is preferred because "when I was in Tokyo" refers to a period of time where the attempts of seeing the movie three times occurred, and had seen would indicate that the actions happened before I was in Tokyo.